Pleasant touch is best when it’s warm, close, soft, and slow

A pleasant touch to his head makes a dog squint and smile.
[1]

CT afferents sense pleasant touch

Unmyelinated afferents responding to light touch were first described in furry animals in 1939. In humans, a similar type of afferents was identified about 50 years later (CT, C tactile).

…the role of CT afferents… is to boost the feeling of pleasantness when touched by a friendly human being.

CT afferents are substantially more responsive to an initial touch stimulus than to succeeding stimuli. It may be speculated that the system is designed to make us more inclined to appreciate a friendly touch when first perceived.

The system would be of significance in supporting feelings of pleasure (reward), confidence, comfort, and security as you are close to your parents, lover, kin, or friends. Moreover, it may have a role in hormonal responses as well as in bonding individuals emotionally together.

Pleasant touch feels best at body temperature 

… afterdischarge in CT afferents is highly dependent on temperature, as it is more frequent and more prominent at lower than neutral temperatures. In a sample of 15 CT units, afterdischarge was seen in 80 % at 15 °C, but in only 13 % at… 32 and 42 °C…

… subjects’ feelings of pleasantness were optimal when the temperature of the moving object was neutral…

Pleasant touch is stronger when it’s closer in

CTs are abundant in the hairy skin of the human body, scarcer in the distal parts of the extremities and seem to be lacking altogether in the glabrous skin.

The pad skin of furry animals which is the homologue of human glabrous skin was primarily designed to take the wear and tear of walking and running.

Pleasant touch feels best when it’s soft

For slow to medium-velocity touch in the left graph, soft touch (open circles) and harder touch (filled circles) produced nearly the same CT response impulse rate. Even so, for slow to medium-velocity touch in the center graph and in the right graph, soft touch was rated as much more pleasant.

The most pleasant touch to CT afferents is relatively slow speed and is soft.

Pleasant touch feels best when it’s slow

… human CT afferents are tuned to a relatively slow speed of movements across the skin…

…in CT afferents maximal rate occurs at a fairly low speed (about 1–3 cm s −1 [0.4 to 1 inch per second]) which corresponds fairly well to human caressing movements.

… subjects’ estimates of pleasantness… are similarly tuned to the speed of movement…

… a prominent and sometimes long-lasting afterdischarge is seen in CTs…[2]


  1. Minette. “Not all Dogs Like Being Petted.” 12 Nov. 2012, http://www.thedogtrainingsecret.com/blog/dogs-petted/. Accessed on 5 Nov. 2016.
  2. Vallbo, Åke, Line Löken, and Johan Wessberg. “Sensual Touch: A Slow Touch System Revealed with Microneurography.” Affective Touch and the Neurophysiology of CT Afferents. Springer New York, 2016. 1-30.

Fall asleep faster by making hands and feet warm

Capillary blood flow in hands and feet rises rapidly at 33 to 34 C, so you fall asleep faster fast.

Fig. 5. Correlation between skin temperature and resting blood flow velocity (CBV) in one nailfold capillary of a healthy 37-year-old man. Notice the marked increase in CBV occurring at 34 C… The figure illustrates that the microclimate of at least 34 C that is created during sleep is essential in order to attain and sustain maximal skin blood flow.

Fall asleep faster by warming your skin

Sleep preferably occurs during the circadian phase of… increased heat loss… due to a profound increase in skin blood flow and, consequently, skin warming.[1]

…to fall asleep a certain comfortable microclimate is necessary.[2]

Sleep-related behavior including the creation of an isolated microclimate of high temperature by means of warm clothing and bedding in humans and the curling up, huddling and cuddling in animals all help limit heat loss.

The use of bed covers… allows for the development of an isolated microclimate of a temperature of even 34–36 C…, effectively limiting heat flow to the environment. Such a high environmental temperature yields an important additional advantage for attaining and stabilizing the high level of skin blood flow. …it is exactly at a temperature increase from 33 C to 34 C that vasodilation and skin blood flow increase steeply to their maximum, as shown in Fig. 5 [above]… The bed microclimate of 34–36 C is thus critical for the maintenance of a high level of skin blood flow, which would be annihilated even with a minute decrease toward 33 C.

… the prolonged period of increased skin blood flow… may support maintenance of the skin as a primary barrier in host defense.[1]

Especially, warm your fingers and toes 

The distal skin regions, in particular fingers and toes, are the main thermoeffectors to lose core body heat…

… warm distal skin temperatures induced… by… selective skin warming predispose to a rapid onset of sleep.[3]

At all times of day, warming using a thermosuit helped people fall asleep faster.

Fig. 4… …every subject was exposed to both slight warming and cooling at all times of day. The thermosuit manipulation resulted in a proximal skin temperature difference between the two conditions of only 0.8… C around a mean of 35.1.. C. In spite of the fact that subjects experienced the warm condition as slightly less comfortable, it accelerated sleep onset latency by 26%… [1]


  1. Van Someren, Eus JW. “Mechanisms and functions of coupling between sleep and temperature rhythms.” Progress in brain research 153 (2006): 309-324.
  2. Kräuchi, Kurt. “The human sleep–wake cycle reconsidered from a thermoregulatory point of view.Physiology & behavior 90.2 (2007): 236-245.
  3. Kräuchi, Kurt, and Tom Deboer. “Thermoregulation in Sleep and Hibernation.” Principles and Practice of Sleep Medicine, edited by Meir H. Kryger et al, Elsevier, 2017, pp. 220-228.e5.

Sudden death can be prevented by self-screening

Views of progression from normal artery to acute myocardial infarction and sudden death[1]

Every year, more than 1 million people in the United States and more than 19 million others worldwide experience a sudden cardiac event (acute coronary syndromes and/or sudden cardiac death). A large portion of this population has no prior symptom.[2]

Preparticipation health screening by self-reported medical history or health risk appraisal should be done for all individuals wishing to initiate a physical activity program. These self-guided methods can be easily accomplished by using such instruments as… an adaptation of the AHA/ACSM Health/Fitness Facility Preparticipation Screening Questionnaire:

Assess your health status by marking all true statements


History
You have had:
­__ a heart attack
__ heart surgery
__ cardiac catheterization
__ coronary angioplasty (PTCA)
__ pacemaker/implantable cardiac defibrillator/rhythm disturbance
__ heart valve disease
__ heart failure
__ heart transplantation
__ congenital heart disease

Symptoms
__ You experience chest discomfort with exertion
__ You experience unreasonable breathlessness
__ You experience dizziness, fainting, or blackouts
__ You experience ankle swelling
__ You experience unpleasant awareness of a forceful or rapid heart rate
__ You take heart medications

Other health issues
__ You have diabetes
__ You have asthma or other lung disease
__ You have burning or cramping sensation in your lower legs when walking short distance
__ You have musculoskeletal problems that limit your physical activity
__ You have concerns about the safety of exercise
__ You take prescription medications
__ You are pregnant

If you marked any of the statements in the section, consult your physician or other appropriate health care provider before engaging in exercise. You may need to use a facility with a medically qualified staff.


Cardiovascular risk factors
__ You are a man ≥45 yr
__ You are a woman  ≥55 yr
__ You smoke or quit smoking within the previous 6 mo
__ Your blood pressure is ≥140/90 mm Hg
__ You do not know your blood pressure
__ You take blood pressure medication
__ Your blood cholesterol level is ≥200 mg ∙ dL-1
__ You do not know your cholesterol level
__ You have a close blood relative who had a heart attack or heart surgery before age 55 (father or brother) or age 65 (mother or sister)
__ You are physically inactive (i.e., you get <30 min of physical activity on at least 3 d per week)
__ You have a body mass index ≥30 kg ∙ m-2
__ You have prediabetes
__ You do not know if you have prediabetes

If you marked two or more of the statements in this section you should consult your physician or other appropriate health care as part of good medical care and progress gradually with your exercise program. You might benefit from using a facility with a professionally qualified exercise staff a to guide your exercise program.


__ None of the above

You should be able to exercise safely without consulting your physician or other appropriate health care provider in a self-guide program or almost any facility that meets your exercise program needs.[3]


  1. Libby, Peter, Paul M. Ridker, and Attilio Maseri. “Inflammation and atherosclerosis.Circulation 105.9 (2002): 1135-1143.
  2. Naghavi, Morteza, and Erling Falk. “From vulnerable plaque to vulnerable patient.Asymptomatic Atherosclerosis. Humana Press, 2011. pp. 13-38.
  3. American College of Sports Medicine. ACSM’s guidelines for exercise testing and prescription. 9th ed., Lippincott Williams & Wilkins, 2014. pp. 23, 25.

Lower hunger by going for lower food insulin index

Food pyramid with many low glycemic index foods at the base and a few high glycemic index foods at the apex

Later in the day, hunger returns more easily.

One way to keep hunger away is to choose foods that are include few or no carbs.

A better way to keep hunger away is to choose foods that have a lower glycemic index (GI), as in the figure above.[1] This way we can include some carbs.

The best way to keep hunger away is to choose foods that have a lower food insulin index. The food insulin index is the insulin demand generated by a food, scaled so that the insulin demand generated by glucose equals 100. Using the food insulin index, we can take into account some low-carb foods that also bring hunger.

The food insulin index varies by food group:

3 – fats and oils
8 – alcohol
22 – meat and protein alternatives
41 – mixed meals
47 – dairy products
49 – vegetables and legumes
50 – fruit and fruit juice
55 – snack foods
56 – french fries
58 – breads, cereals, grains, rice, and pasta
63 – beverages
71 – candy
100 – glucose

Meats, nuts, and cheese—whose food insulin index is markedly lower—are easy to remember late in the day to keep hunger away. But this amounts to just avoiding carbs. With the food insulin index, we can do better.

Within most of the food groups, the food insulin index of individual foods varies a whole lot. This lets us look over each food group and start choosing and remembering new favorites.

Food insulin index values of various foods, grouped by food type, in a bar graph[2]

So sometimes instead of the usual cheeses, nuts, or jerky, you might want to try having some whole-grain crackers, Snickers bars, chocolate chip cookies, or regular potato chips.


  1. Bao, Jiansong, et al. “Food insulin index: physiologic basis for predicting insulin demand evoked by composite meals.The American journal of clinical nutrition 90.4 (2009): 986-992.
  2. Bell, Kirstine (2014). Clinical Application of the Food Insulin Index to Diabetes Mellitus (Doctoral dissertation).

Hunger returns quicker cause insulin is lower as the day goes on

Food choices shown here change as the day goes on to help keep hunger away.. [1]

Hunger is controlled by many hormones.[2] One factor we can control is what we eat, and when.

In an early study, increased insulin increased hunger.[3] In later studies in mice, though, insulin reduced hunger.[4] Also in a later study in women, insulin reduced hunger. It even reduced the tastiness of the tastiest snack offered, chocolate chip cookies. Sounds definitive.[5]

The same foods lead us to produce different amounts of insulin at different times of day. A given food produces a stronger insulin response in the morning than in the afternoon and evening, as shown in the figure.

Graph shows how the insulin response to food differs at 9 am, 3 pm, and 8 pm.
[6]

  • At 9 am the insulin response is fast, high, and long.
  • At 3 pm the insulin response is slow, medium, and long.
  • At 8 pm the insulin response is slow, low, and short.

The insulin response reduces hunger most in the morning, less in the afternoon, and least in the evening.

This is great news! Forewarned is forearmed.

We can satisfy our hunger equally well throughout the day by splurging in the morning, being more careful in the afternoon, and being most careful in the evening.


  1. “Welcome to Northside Grille.” HudsonNorthSideGrille.com. Accessed 29 Oct. 2016.
  2. Schwartz, Michael W., and Gregory J. Morton. “Obesity: keeping hunger at bay.” Nature 418.6898 (2002): 595-597.
  3. Rodin, Judith, et al. “Effect of insulin and glucose on feeding behavior.” Metabolism 34.9 (1985): 826-831.
  4. Piroli, G. G. “Regulation of food intake: an ‘old’ actor plays a ‘new’ role.Molecular psychiatry 8.4 (2003): 364-365.
  5. Hallschmid, Manfred, et al. “Postprandial administration of intranasal insulin intensifies satiety and reduces intake of palatable snacks in women.Diabetes 61.4 (2012): 782-789.
  6. Jarrett, R. J., et al. “Diurnal variation in oral glucose tolerance: blood sugar and plasma insulin levels morning, afternoon, and evening.Br Med J 1.5794 (1972): 199-201.

Alcoholism is biggest factor in divorce in 75-year study

Long-term marirages were mostly free of alcoholism.
A lifelong study began with privileged people

This… is about how a group of men adapted themselves to life and adapted their lives to themselves. It is also about the Grant Study, now seventy-five years old, out of which this story came.

The first subjects were 64 carefully chosen sophomores from the all-male Harvard College classes of 1939, 1940, and 1941, who took part in an intensive battery of tests and interviews. That first group was joined by sophomores from the next three Harvard classes…

Marriages provided few clues at first

In 1977 I handed in the manuscript of Adaptation to Life. My editor at Little, Brown, Lewellen Howland, took issue with my contention that divorce was a serious indicator of poor mental health, and suggested gently, “George, it is not that divorce is bad; it is that loving people for a long time is good.” I liked his sentiment, but I didn’t believe him, despite the fact that I myself was in a happy second marriage at age forty. (We’re all the exceptions to our own rules.)

The numbers I’d been working with for the previous ten years didn’t look promising at all. By 1967, seventeen men had divorced. By 1973, fourteen of them had been remarried for longer than a year. Of those fourteen second marriages, eight had already ended in divorce again—you’ll hear about two of those in a little while—and four more showed weaknesses that kept them securely out of the good marriage category. In other words, of the fourteen remarriages, only two looked to be anything like happy, and they were still too new to be trusted. Louie’s a romantic, I thought. All I have to do is wait for thirty years and I’ll be able to show him his error.

Fifteen years later I was still right and Howland was still wrong. When I checked marital history against the best and worst Adult Adjustment Outcome determinations that I had established for that 1977 book, all of the fifty-five Best Outcomes had gotten married relatively early and stayed married for most of their adult lives. (And by the time those men were eighty-five, we learned later, only one marriage had ended in divorce.) In contrast, among the seventy-eight Worst Outcomes, five had never married, and by seventy-five years of age, thirty-five (45 percent) of the marriages had ended in divorce. Proportionately three times as many of the Best Adjusted men enjoyed lifelong happy marriages as the Worst Adjusted.

But as the first decade of the twenty-first century wound to a close, the men were well into their eighties and the Study was still going strong. And so were a bunch of second marriages. I could no longer get away with my flippant dismissal of Louie’s rebuke. I was also intrigued by a growing sense that as the men got older they talked about their marriages differently. So in 2010, after many years of concentrating mostly on aging, I took another look at marriage. This time I was armed with a great deal of information about alcohol use among the men and their wives (which I’ll detail in Chapter 9). And it turned out that Lewellen Howland was a very wise man.

Once again, the long picture was quite different from the shorterterm one. Not about everything. At eighty-five, twenty-six of the twenty-eight men with consistently happy first marriages reported that their marriages remained happy. Marriages that had been poor to start with tended to remain that way, whether they endured without divorce for fifty years or ended, still unhappy, in death. Of the thirty surviving men who had had unhappy marriages between twenty and eighty years of age, only five reported happy marriages after eighty. Four of these were new marriages, undertaken after the first wife had died. None of this was very startling (with the exception of the fifth husband’s mysterious report that he and his wife were “still in love, mutually dependent and the best of friends”). But it was very startling, to me at least, that twenty-three of the twenty-seven surviving divorced and remarried men reported that their current marriages were happy—and had been for an average length of thirty-three years!

68 years in, a new factor in divorce emerged – alcoholism

What magic had occurred in those final years to shed such a different light on the early statistics? None. It was just that a new calculation had cleared away a lot of obscuring underbrush. On second thought, though, maybe it was magic after all—the magic of lifetime study.

…the single most important factor in the Grant Study divorces was alcoholism; thirty-four of the divorces—57 percent—had occurred when at least one spouse was abusing alcohol.

…it looked very much as though alcoholism in a marriage often caused not only the divorce, but also the failed relationships, the poor coping style, and the evidence of shaky mental health.

Alcoholism is still, arguably, the most ignored causal factor in modern social science, and it took the Grant Study sixty-eight years to notice that it was the most important cause of failed marriage.[1]


  1. Vaillant, George E. Triumphs of experience. Harvard University Press, 2012.